The following description relates to a steer-by-wire system, and, more specifically, to a system to provide torque feedback in a steer-by-wire system.
In steer-by-wire systems, mechanical devices with linkages and mechanical connections are replaced with sensors, actuators, and electronics. For example, in a conventional steering system, which includes a steering wheel, a steering column, a power assisted rack and pinion system, and tie rods, the driver turns the steering wheel which, through the various mechanical components, causes the road wheels of the vehicle to turn. In the steer-by-wire system, a number of the mechanical components between the steering wheel and the road wheels of the vehicle are replaced with a sensor at the steering wheel and both sensors and actuators at the road wheels, and the rotation of the steering wheel is measured by the sensor. This rotation measurement is processed by the electronics to generate command signals for the actuators to turn the road wheels. Driver feedback in the form of steering torque that is designed to represent the feel of the road is provided by torque and rotation servo-actuators with software that provide simulation of driving conditions for the driver.
Some passenger vehicles are equipped with an advanced driver assistance system (“ADAS”). Such vehicles are configured to perform operations without continuous input from a driver, such as steering, accelerating, and braking. When the ADAS system is active, the steering wheel is not required for vehicle control. However, the driver may switch between the autonomous and non-autonomous driving conditions, and in the non-active state of the ADAS system, the steering wheel is again required for use by the driver.
Accordingly, it is desirable to provide alternative driver feedback systems for steer-by-wire systems regardless of autonomous capability.